The present invention relates generally to pavement marking, and more particularly to the line width and thickness mechanisms for a thermoplastic line striper.
Alkyd and hydrocarbon thermoplastics are commonly used to mark pavement surfaces with visible lines and symbols such as lane dividers and guide lines. In particular, thermoplastics provide a durable alternative to pavement painting, and are commonly used to mark street intersections, parking lots, and other high-traffic pavement surfaces from which paint would quickly wear away.
Thermoplastics are conventionally applied to pavement surfaces using a mobile applicator comprising a heated reservoir or kettle, and an application screed die. Melted thermoplastic is dispensed from the kettle at a controlled rate and applied in a thin layer atop pavement surfaces with the screed die. Conventional thermoplastics must be brought to melt temperatures of 177 to 250° C. (350 to 480° F.) prior to application. Existing systems use a central mixer-melter to bring thermoplastics to these temperatures. Once melted, a load of thermoplastic from the central mixer-melter is transferred to the kettle of a mobile applicator for pavement marking. The applicator kettle is heated to prevent thermoplastic from resolidifying before it is applied to the pavement surface. Often, a single central mixer-melter may service a plurality of applicators on a job site.
In general, governmental regulations determine the thickness of the thermoplastic being applied to the road surface. In addition, other environmental factors can change the application parameters (such as ambient temperature and surface roughness). Governmental regulations also generally determine the width and number of stripes that are applied. In existing systems, the width of the screed die box determines the width of the stripe of thermoplastic being applied. A modular screed die box allows the user to compensate for such variables.